1. Field of the Invention
The present invention relates to a technology for reading an image with a capability of determining a user who read a document.
2. Description of the Related Art
When a user reads a document and prepares an image file by using a scanner, some means can inform a date and time when the file is prepared based on the file preparation time. However, these means cannot inform who has read the document. Japanese Patent Application Laid-open No. H5-145714 discloses a technique that makes it possible to selectively print symbols or characters to confirm a reading of the document on both the front side and the back side of the document. According to this conventional technique, fixing units that fixedly hold printing units are provided at both sides of the document to sandwich the document so as to detachably hold the printing units at a printable position on the front side and at a printable position on the back side of the document, respectively.
Nowadays, read image data are held as files on a personal computer or a server in many cases. On the other hand, according to the invention described in Japanese Patent Application Laid-open No. H5-145714, the read image data cannot be distinguished as a file because symbols or characters are printed on the document. When the read image data is stored as a file, it becomes difficult to determine who has read the document when the file is stored in a personal computer or a server used by many users.